(1)The length of any sentence of imprisonment imposed on an offender by a court shall be treated as reduced by any period during which he was in custody by reason only of having been committed to custody by an order of a court made in connection with any proceedings relating to that sentence or the offence for which it was passed or any proceedings from which those proceedings arose, but where the offender was previously subject to a probation order, an order for conditional discharge or a suspended sentence in respect of that offence, any such period falling before the order was made or suspended sentence passed shall be disregarded for the purposes of this section.
(2)For the purposes of this section a suspended sentence shall be treated as a sentence of imprisonment when it takes effect under section 40 of this Act and as being imposed by the order under which it takes effect.
(3)No period of custody, other than a period which would have been taken into account before the commencement of this Act under section 17(2) of the [1962 c. 15.] Criminal Justice Administration Act 1962 (duration of sentence) for the purpose of reducing a term of imprisonment, shall be taken into account for the like purpose under this section unless it falls after the commencement of this Act.
(4)Any reference in this Act or any other enactment (whether passed before or after the commencement of this Act) to the length of any sentence of imprisonment shall, unless the context otherwise requires, be construed as a reference to the sentence pronounced by the court and not the sentence as reduced by this section.